1. Field of the Invention
This invention relates to impellers and particularly to an impeller having an end piece on an insert to aid in installation and removal of flexible impellers from pump housings.
2. Description of the Related Art
Flexible impellers are installed on a shaft in pump housings. The fit of the impeller into the pump must be with some squeeze of the blades. This arises from the cam. It provides the displacement of the impeller. In addition the need to provide some degree of initial impeller compression is necessary to account for slip. Thus the installation of such an impeller is with a fair amount of force to overcome the deflection of the blades while simultaneously pushing or pulling the impeller into the pump. In the case of installation the impeller must be inserted with a twisting motion to align the impeller insert with the key, spline or other drive mechanism located on the shaft. When removing an impeller the problem is compounded in that some means must be found to initially grip the impeller to pull it, as the impeller is flush with the housing. Most often an impeller is removed because it is worn and has been in the housing for some period of time. Flexible (rubber) impeller pumps are extensively used in the marine industry as raw water coolant pumps on small boats. Often used impellers will be encrusted with silt and salt. This makes the initial pull from the pump more difficult. The difficulty increases dramatically with larger impellers and is compounded with the physical restrictions often imposed by the location of pumps in confined engine compartments of boats.
A number of methods have evolved over the years to remove impellers from pumps. A simple technique is to use two pair of pliers. Two impeller blades are gripped on either side using the pliers. They are then pulled out. For a tough impeller two screwdrivers can be used to pry the impeller from a stuck position.
For large impellers or impellers stuck on a shaft the above techniques can prove to be inadequate. This forces the user to either remove the pump from the location and work on impeller removal from a workbench, or to use an alternate method of impeller removal. Removing the pump from the engine is not always practical. An example of such a situation is changing a failed impeller while a boat is at sea. One removal tool used works very much like a bearing-puller. To grip the hub of the impeller through a screw mechanism and then the impeller is pulled off the shaft by another screw pushing against the pump shaft. Although this tool is effective it is expensive and usually found only in the professional mechanics toolbox.
An alternate method used is to provide for a thread on one end of the insert of the rubber impeller. A bolt or screw is threaded into the treaded end of the insert. It is screwed in until it pushes against the shaft and jacks the hub or impeller from the bore. This is a technique used for removing blower hubs and other such hubs that have either a tight fit or may become jammed on a shaft over time. Although it has proven to be an effective technique there are two disadvantages to it. In marine applications where the impeller is in salt water the thread can become corroded. This can prevent the method from working. In addition the need to tap the end of the impeller insert adds cost to the manufacture of the rubber impeller.
The invention comprises an insert for a flexible (rubber) impeller designed to be used with an inexpensive removal tool. The insert has a drive mechanism built into the bore such as a spline, keyway, flat or other mechanism. The insert also has an internal bore and an end piece with one or two flanges or ears at one end. The ears have a step to allow for a stop.
The insert has external lugs axially to provide a mechanical grip to the rubber after molding.
The impeller insert, when installed on a shaft in a pump, will have clearance between the two ears and the end of the shaft, or in a second embodiment between one ear and the end of the shaft.
A special tool can be used to engage the impeller by being inserted and locked through a twisting action into the ear or between the ears at the end of the impeller.
The tool is used to pull the impeller from the housing. The tool is of a special design that allows a stuck or tight impeller to be initially freed from the housing by rocking the tool.
An alternate tool is also provided for difficult impeller removal. By the use of a screw mechanism in the tool a difficult impeller can be jack screwed from the pump.
In another embodiment a tapped hole is provided in the pump shaft for purpose of impeller installation. A special installation tool is placed through the impeller. The tool with the impeller is threaded into the hole. The impeller is then forced into the hole by turning the installation tool drive nut forcing the insert onto the pump shaft by pressing on the ear.
An additional installation tool consists of an, alignment cone. When placed in front of an open pump it allows the flexible impeller to be forced to the shape of the housing as it is pushed through the cone.
It is an object of the invention to provide for easily installing the flexible impeller on a shaft in a pump housing.
It is an object of the invention to provide for easily removing the flexible impeller from a shaft in a pump housing.
It is an object of the invention to provide an ear on the end of the impeller insert for use with a tool for removing and installing the impeller insert on a pump shaft.
It is an object of the invention to provide a tool for twisting or rocking the insert on the pump shaft to loosen it.
It is an object of the invention to provide a tool with a handle for twisting or pulling the impeller insert from the pump shaft.
It is an object of the invention to provide a tool with a leverage slot for pulling the impeller insert from the pump shaft.
It is an object of the invention to provide a tool with a screw jack for pulling the impeller insert from the pump shaft.
It is an object of the invention to provide a tool with a screw jack for installing the impeller insert from the pump shaft.
It is an object of the invention to provide an alignment cone for installing the impeller insert from the pump shaft.
It is an object of the invention to provide a flexible impeller installation and removal method that provides for an inexpensive tool and methodology for installing and removing flexible impellers in pumps.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.